The presence of mycotoxins, secondary metabolites of toxic fungi, in agricultural commodities is worldwide a major problem. According to the Food and Agricultural Organization (FAO) estimates, 25% of the world's food crops are affected by mycotoxin producing fungi (Rasch, Kumke, & Löhmannsröben, 2010). The most important mycotoxins in food and feed production, that pose a major threat to public health and agro-economy, include aflatoxins, deoxynivalenol (DON), ochratoxin A, fumonisin, zearalenone, patulin and T-2 toxin (Miller, 1995; Traar, 2013).
DON is among the most prevalent mycotoxins and is mostly produced by the moulds fusarium graminearum and fusarium culmorum. It frequently occurs on cereal commodities, like wheat, maize, barley, oats and rye, which can be infected before or after the harvest (Sobrova et al., 2010). Moreover, because DON cannot be destroyed during food processing, like cooking, freezing and roasting, it appears both in the raw and processed products. The ingestion of DON-contaminated products can cause acute and chronic health effects such as diarrhea, nausea, immunosuppression and neurotoxicity (Abysique, Tardivel, Troadec, & Felix, 2015; Pestka, 2007). The detection of DON is an important issue in the food industry, because it is present in more than 90% of all mycotoxin-contaminated cereal samples and its occurrence is considered to be an indicator of the presence of other mycotoxins. (Ran et al., 2013)
DON is an important contaminant of maize (Pleadin et al., 2012) and maize is the staple food in many countries. Currently, the presence of DON in food and feed products is strictly regulated in most regions of the world. Regarding raw maize kernels, the European Commission states the maximum allowed DON concentration to be 1750 ppb, while in the USA and China a limit of 1000 ppb of DON is imposed (European Commission, 2007). To fulfil these limits, the presence of DON is nowadays mostly detected by the use of chemical analyses, like liquid chromatography—tandem mass spectrometry (LC-MS/NIS) and enzyme-linked immunosorbent assays (ELISA). However, these analytical techniques are time-consuming, expensive and destructive (Ran et al., 2013). Due to the uneven presence of the toxin in both the food products and the crops, these sample-based analyses often give a limited view on the degree of contamination. It is an aim of the present invention to provide a non-destructive spectroscopic method that can be used to screen individual, cereal kernels and other food products suseptable to contamination with non-fluorescent mycotoxins.
Spectroscopic detection techniques are already widely used in agriculture and chemical industries for the determination of organic compounds in matter, like proteins, moisture, starch and pigments (Baye, Pearson, & Settles, 2006; K. C. Volkers, M. Wachendorf, R. Loges, N. J. Jovanovic, 2003; Meulebroeck & Thienpont, 2012). To date, there is a high interest to apply the spectroscopic detection techniques for the identification of DON. The use of Fourier-transform near- and mid-infrared (FT-NIR and FT-MIR) spectroscopy for the detection of DON in wheat and maize is already widely discussed (Abramović, Jajić, Abramović, Ćosić, & Jurić, 2007; De Girolamo, Cervellieri, Visconti, & Pascale, 2014; Kos, Lohninger, & Krska, 2003). However, current published measurements use homogeneously contaminated, grinded samples and require the use of chemometrics to classify the samples into their various contamination levels. It is an aim of the present invention to provide a spectroscopic method that enables the measurement of the localized contamination in unground, individual cereal kernels, such as maize kernels. Furthermore, due to its vibration sensitivity, Fourier-transform spectroscopy can hardly be implemented in an industrial environment.